1. Field of the Invention
The present invention relates to a model defining method for defining a model for simulating a behavior of economy, society or the like regarded as a system, the model representing a relation between phenomena and events between constituent elements of the system, as a causal relation.
2. Description of the Related Art
In order to speed up decision making such as what price is to be set to a new product and whether or not a business system is incorporated, it is important to estimate the effects quickly through simulation. For example, when a price of a new product is to be determined, it is desired to estimate how the number of orders changes with the price set to the new product and influences the final sales. In modeling the phenomenon propagating and changing chains of causal relation such as price, the number of orders, and sales, it is desired to model the structure of causal relation itself.
As a conventional method of simulating the behavior such as social phenomena by using the structure of causal relation, system dynamics are known which have been developed by Forrester at MIT.
DYNAMO is known as a simulation language of system dynamics. A simulation program is configured by using a rate variable representative of a flow rate of articles per unit time and a level variable representative of an accumulation amount of flow rates, and setting an equation to these variables. The causal relation can be expressed by regarding the causal relation as a relation between the rate variable and level variable.
In modeling simulation, the equation has been set conventionally while the structure of causal relation easy to be understood by human is translated into a conventional simulation language. It takes therefore a time to develop a simulation program. Since the simulation program has poor readability, reuse and modification thereof are difficult.